Following a capsize, the crew uses lines rigged to the boat to right themselves with help from a chase boat. Photo: Abner Kingman

Despite their power, the wing sails can be de-tuned, to swing peacefully at a mooring overnight, ready for action the next day. Photo: Gilles Martin-Raget

America's Cup 101: A primer for beginners explaining the history of the event and the technology underpinning the wing-sail catamarans that will compete in the 34th America's Cup in San Francisco in 2013. Video: America's Cup

Highlights from the final day of racing at Newport, Rhode Island, on July 1. Video: America's Cup

The America’s Cup has come to San Francisco … a year early. The race for the Cup starts next summer, but the America’s Cup World Series — essentially a dress rehearsal — is on now, and it’s awesome.

The World Series features the same teams, the same courses and even the same boats (sort of) we’ll see racing in San Francisco next year. It’s also an excellent primer on one of the coolest, costliest and most technologically advanced sports on the planet.

Larry Ellison and Team Oracle won the last America’s Cup in 2010. One of the eccentricities of the oldest trophy in sport is that whoever holds the cup controls the next race. It’s like letting the winner of the Super Bowl run the NFL the following season. This means Ellison is not only defending the Cup, he’s setting the rules.

Being an entirely different type of billionaire than the East Coast captains of industry who historically dominated the sport, the first thing Ellison did was toss more than 150 years of tradition overboard. The boats we’ll see racing next year are not the stately soft-sailed monohulls of yore, but wing-sailed catamarans — jittery high-tech carbon fiber monsters that are far faster and more punishing than anything ever raced in the Cup. The action will be much more exciting for spectators, because crashes are more likely. You think NASCAR pile-ups are cool? Watch a catamaran capsize.

It was a bold, unprecedented move, a technological leap from the 19th to the 21st century. A new race needed a new slogan: “The Best Sailors. The Fastest Boats.” There was only one problem — the best sailors in the world didn’t know how to sail the fastest boats in the world.

Thus, the World Series.

The series features the AC45, half-size versions of the boats we’ll see raced next year in Cup races. The AC45, named for its length, is 70 feet tall, 22.6 feet wide and weighs 3,086 pounds. It takes five people to race one. As impressive as those figures are, they pale compared to the AC72. It’s bigger, faster and meaner, with a crew of 11 and a top speed north of 30 knots.

There are 11 boats racing in the Bay, which begs the question of who to root for. That depends on what kind of person you are. The smart money is on Team Oracle’s lead boat (they have two in the race) skippered by Jimmy Spithill. The underdog is the JP Morgan boat (only in the America’s Cup could JP Morgan be an underdog!) skippered by Ben Ainslie, fresh from the 2012 Summer Olympics and his fourth gold medal. Ainslie is considered the best sailor in the world, but he has precious little experience with the AC45. Spithill, no slouch of a sailor himself, has the most experience. Ainsley will join Team Oracle after the World Series ends in May, so what you’re watching is a fight to skipper next year’s defense of the Cup.